greenawalt



March 3, 1964 J. E.`GREENAWALT 3,123,284

sucTIoN FAN Filed sept. 5, 1961 5 sheets-sheet 1 March 3, 1964 J, E, GREENAWALT 3,123,284

sUcTIoN FAN i Filed Sept. 5, 1961 5 Sheets-Sheet 2 March 3, 1964 J. GREENAWALT 3,123,284

SUCTION FAN Filed Sept. 5, 1961 5 Sheets-Sheet 5 March 3, 1964 J.v E. GREENAWALT SUCTION FAN 5 Sheets-Sheet 4 Filed sept. 5, 1961 FIG FIG.4

. Filed Sept. 5, 1961 March 3, 1964 J. GREENAwAL-r- 3,123,284

SUCTION FAN 5 Sheets-Sheet 5 FIGS-,3.5 F|^G.8

FIGLIOl .F l GJI United tates Patent @ffice 3,123,284 Fatented Mar. 3, 1964 3,123,284 SUCTION FAN John Eckert Greenawalt, Bronxville, N.Y., assigner to Greenawalt Sintering Co., Inc., New York, N.Y., a corporation of New York Filed Sept. 5, 1961, Ser. No. 135,807 Claims. (Cl. 230-128) This invention relates to centrifugal blowers or fans and, more particularly, to improved dilfusers for obtaining increased pressure or suction.

In one conventional type of blower used for example, for applying suction to a sintering machine, the blower comprises an involute chamber surrounding a diffuser which in turn surrounds the impeller. Rotation of the impeller draws gases axially of the impeller into its blades, and the blades discharge such gases through the diffuser into the involute chamber, whence the gases are discharged from the blower. In such blowers as heretofore constructed, the cut-otf edges of the diffuser blades are comparatively sharp and narrow as measured in a circumferential direction. According to a preferred form of the present invention, these cut-olf edges are extended circumferentially beyond the cut-olf point for a considerable distance, comparable to the distance between impeller blades. This construction provides a more positive seal to the flow of gases between diffuser nozzles, and has other advantages as will be more apparent as the description proceeds.

Objects of the present invention are thus to improve the amount of suction obtained from such a blower, and in general to improve construction and operation of gas blowers or compressors.

Other objects and features of the invention will be more apparent from the following description when considered with the following drawings in which:

FIG. l is a front elevation, with parts broken away, of a blower according to the invention;

FiG. 2 is a vertical cross-section through the blower, taken on the line 2 2 of FIG. l;

FIG. 3 is a plan section with top of the housing removed, taken on line 3-3 of FIG. 2;

FIG. 4 is a side elevation of one of the fan disks forV cooling the blower bearings;

FIG. 5 is an end elevation of the fan disk of FIG. 4;

FIG. 6 is a section taken through the diffuser, shown disassembled from the blower, taken on a plane perpendicular to the blower axis;

FIGS. 7 to l2 are detail sections, taken on the lines 7-7 to 12-12 respectively of FIG. 6, illustrating the construction of the diffuser nozzles.

In the following description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In the accompanying drawings and description forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring now to the drawings, and more particularly to FIGS. l, 2 and 3, the blower will first be only generally described. As illustrated, it rests at a foundation 1t? which has a high tower block 11 for electric drive motor 18.

The blower comprises a frame or housing 12 having a diffuser 35 surrounding an impeller 13. The impeller is mounted on main shaft 14 which is journalled in bearings 16 and 17. Shaft 14 is connected to the shaft of motor 18 by coupling 19. Shaft 14 supports fan disks 20, 21 for cooling the bearings 16 and 17. The blower has a bottom inlet passage 22 in register with an opening passing through the foundation 10, and a discharge passage 23 at the front of the blower.

The blower will now be described more in detail. The housing 12 is split vertically into right and left sections, and is split horizontally into a base 29 and top 30. The right and left sections are connected by bolted coupling ilanges 27 and the base 29 and top 3l) are connected by bolted coupling flanges 28, as will be understood by those skilled in the art.

The base 29 comprises ribbed walls 31, 32; these support the blower bearings 16 and 17. The housing 12 comprises an involute or flaring scroll 36, whose larger end connects with front discharge 23 and whose smaller end is separated from discharge 23 by a removable baille 33.

The involute 36 is generally rectangular in crossesection, as shown in FIG. 1, and its cross-sectional area flares as shown in FIG. 2. It has annular radial sealing flanges 37 which enclose the discharge ends of the iinpeller blades 50 as described more at length below. The bottom inlet 22 connects with inlet passages 34 which straddle the involute 36 and connect with circular entrance chambers 38 disposed on either side of the impeller 13.

Referring now also to FIGS. 6 to 12, the diffuser 35 is made in two half sections connected by coupling flanges 41. The diffuser has a series of spiral blades 40 forming diverging or flaring nozzles 42. The inner or entrance ends of blades 40 have extended separating surfaces or lands 43. The lands 43 extend from the shearing edges 45 circumferentially for considerable distances, and are laid out on a fixed radius whose center 14a is a center of shaft 14. These lands 43 are discussed more at length below.

The inner edges of the diffuser 35 have annular flanges 44 which rest upon seats 46 of the involute 36. The sealing flanges 37 and diffuser 3S form a runway for the impeller blades 50.

The wheel or impeller 13 has a hub 47 keyed to shaft 14. It has a central plateelike member 48 with projecting web extensions 52 and a series of radial blades 50. The inner or entrance ends of the blades are tapered as at 49 (FIG. 1). The outer or discharge ends of the blades 50 fit in the runway between the sealing flanges 37, as indicated especially in FIGS. 1 and 3.

The clearance spaces or gaps between the impeller blades 50, on the one hand, and the sealing flanges 37 and the lands 43, on the other hand, are as thin as is practicable.

The housing 12 has seals 51 where the shaft 14 passes through. Adjacent these seals are heat-conducting fan disks 2l), 21. These disks are preferably made of copper or other good heat-conducting material.

The heat-conducting fan disks 2&1 and 21 Vare identical except that one is right handed and the other is left handed; hence, only one will be described in detail. The disk is split at 53. Each disk comprises Ia hub 54 rigidly secured to the shaft 14, blades 55 and openings 56. The blades 55 are arranged .at such `angle that the fan disks generate currents of air which flow in a direction toward their respective bearings 16 4and 17.

In operation, lthe electric motor 18 drives the impeller 13 in the direction of the arrow `58 in FIG. 2. Gas is drawn in through the bottom inlet 22 through the dual inlet passages 34, and into the inlet chambers 38 at either end of the impeller 13. Air is drawn in by the impelle-r blades 50 and discharged from them into the nozzles 42 of the diffuser 35 and delivered to the involute 36 and thence to front discharge 23.

As stated above, an important feature of the invenamazes tion is the extended cut-oil` surfaces or lands 43 on the diiser. In similar blowers, yas heretofore constructed, the cut-oli edges of the diffuser blades were sharp and narrow (in a circumferential direction) whereas in the present blower, the cut-off surfaces or lands 43 are cxtended circurnferentially beyond the cut-oi points 45 for a considerable distance.

To obtain the most desirable results the circumferential length of the lands i3 should equal the peripheral distance between the ends o the impeller blades as shown in FIG. 2. However, the maximum length of the lands should not exceed one-half the distmce between the cuto or yshear points 4S of successive blades of the diffuser.

By vway of further explanation of the operation of a blower constructed according -to the invention, it may be noted that during .the time the blades Sti pass over the surface of lands 43, the outward flow of gases near the surface of the blades is halted for an instant or very brief time and thereby the gases adjacent the blades receive the full Velocity yof the blades S0, so that a substantial length of the lands is necessary -or most efcient results. As the length of the lands is ldecreased, the effectiveness of the desired action is decreased but even an increase of l5% in length of the lands beyond the shear points 4S produces materially better results than the sharp or narrow cut-off edges of the ditusers of prior art blowers.

rl`he following further explanation of the function or" the extended lands d3 is given in an effort to clarify the operation of the invention and should not be interpreted in a limiting sense. Regardless yof theory, the operation is greatly improved as shown by the tests described hereinafter.

rihe improved operation is also thought to be due, at least in part, to the fact that the lands 43, and the small clearance between tips of the impeller blades 51B and the surfaces of the lands, reduces to a minimum the recirculation of Iair between the blades of the impe-.ller i3 and the blades of the diffuser 35. This creates a more positive seal to the flow of gases. During the time the impeller blades 5t) pass over the lands 43, the discharge flo-w of gas from the impeller is partially blocked or obstructed so that the centrifugal force applied by the impeller produces localized compressions. This increases the delivered static pressure or suction of the blower and improves eiciency.

The following tests show the effectiveness of the extended lands 43, as compared with the sharp cut-oli? edges of the prior art. Both tests were made with two blowers in series. In both cases blowers were the same except for the ditlusers; the temperature of the gases was approximately 350 F. and the power consumption and volume ilow rate were the same.

With the regular or standard diiuser, with the sharp cut-oil edges, the resulting suction of the two fans in series maintained a column of water 70` inches high, where-as, with the improved diffuser of the invention, the resulting suction of the two ans in series maintained a column of water 80 inches high.

The dimensions and proportions of .the several parts may be varied widely according to power, rotational speed, suction, pressure and volume desired. As an example, in the form shown which is designed for a sintering machine operation, the impeller 13 has a speed of from 150'() to 1700 r.p.m. The motor l is 800 HJ?. The impeller diameterris 63 inches. The end clearance of the impeller blades with the lands 43 is one-quarter of an inch. The lands i3 are 13.5 inches in ylength (ci-rcumferentially of impeller movement), and the blades are 1 8 inches wide at their ends (axially of shaft 14). rihere are lll impeller blades Sil and 6 diduser blades 4l?.

While certain novel features of the invention have been disclosedV herein, and are pointed out in the annexed claims, it will be understood that, in yaccordance with d the doctrine of equivalents, various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit oi the invention.

What is claimed is:

1. ln a blower for moving gases to provide a suction on the intake side, a housing, an impelier journaled yfor rotation in said housing, said impeller having radially disposed blades, said impeller blades having entrance ends `and discharge ends, a diiluser comprising a plurality of spiral blades forming spiral, outwardly ilared discharge nozzles therebetween, said diuser blades having inner entrance ends and discharge outer ends, said diffuser blades entrance ends being disposed .adjacent said irnpeller blades discharge ends and each having a land extending a substantial distance circumferen` 'ally from its innermost cuto edge, said lands having a fixed radius throughout their lengths measured from the axis of rotation of said impeller and the circumferential length of each of said lands not exceeding one half the circumferential distance between the cutoi edges of successive diffuser blades, said housing being involute in shape and having an entrance chamber adjacent said impeller blade entrance ends, said housing having a discharge chamber adjacent the discharge ends of said diluser nozzles, said diffuser being further characterized by its -I'ixed radius lands having constant clearance gaps between the discharge ends of the impeller blades throughout the lengths of said lands `and said lands being of suiiicient length in relation to the distance between tip ends of successive impeller blades :and said clearance gaps being sufficiently small to briey halt outward ow of gases moved by said impeller so .that the gases moving adjacent the impeller blades receive the full angular velocity of the tip ends of the impeller blades prior to entering said spiral discharge nozzles.

2. In a blower of claim l the circumferential length of said lands being approximately equal to the distance between the tip ends of successive impeller blades and the circumferential distance between the cutoff edges of successive diffuser blades being at least twice the circumferential length of said lands.

3. In a blower of claim 2 the circumferential length of said lands being between 15% and 50% of the circumferential distance between the cutoff edges of successive diffuser blades.

4. in a suction blower, for moving gases, a housing, an impeller journaled for rotation in said housing, said impeller having a central web with radially disposed blades extending on either side thereof and outwardly thereof, said housing comprising an involute discharge chamber surrounding the tip ends of the blades of the impeller, said discharge chamber having an inner wall, said inner wall having sealing flanges having seats and disposed on either side of said impeller blades providing a circular runway for said impeller blades, said housing having entrance chambers defined by said sealing ilanges, said entrance chambers being located on each side of said impeller, a diffuser surrounding said inner wall adjacent said scaling ilanges, said diffuser comprising a plurality of spiral blades seated in said seats and forming divergent spiral discharge nozzles therebetween, said diiluser blades at their inner ends having lands disposed outwardly of and adjacent the tips of said impeller blades, said lands extending a substantial distance circumferentially, and throughout their lengths having the same radius measured from the axis of the rotation of said impeller thereby providing constant clearance with the tips of said impeller blades` throughout the circumferential lengths of said lands, and each of said lands having a circumferential length of at least 15% but not exceeding 50% of the circumferential distance between the cutofr" edges of successive diiuser blades, the circumferential distance between the tip ends of Vsuccessive radial blades of said impeller being substantially less than the circumferential distance between the cutoff edges of successive diffuser blades, whereby the ilow' 5 of gases moved by said impeller radially outward is briey halted by said lands so that there is imparted to the gases moving adjacent the impeller blades the full angular Velocity of the tip ends of said impeller blades prior to the discharge of said moving gases into said spiral discharge nozzles.

5. In the suction blower of claim 4, said lands having a circumferential length approximately equal to the circumferential distance between the tip ends of successive irnpeller blades.

References Cited in the le of this patent UNITED STATES PATENTS 958,765 Prindle May 10, 1910 973,782 Hayton Oct. 25, 1910 1,041,511 Rice et al Oct. 15, 1912 6 Greenawalt Apr. 6, 1918 Hertzler June 3, 1924 Nusim May 5, 1925 Schmidt Feb. 14, 1928 Puffer June 2, 1936 Rupp Aug. 4, 1942 Whittle July 16, 1946 Goddard Mar. 29, 1949 Lawrence Oct. 2, 19156 Pawlicki Oct. 11, 1960 FOREIGN PATENTS Great Britain of 1910 Great Britain June 17, 1926 Great Britain June 17, 1926 Austria Sept. 10, 1925 

1. IN A BLOWER FOR MOVING GASES TO PROVIDE A SUCTION ON THE INTAKE SIDE, A HOUSING, AN IMPELLER JOURNALED FOR ROTATION IN SAID HOUSING, SAID IMPELLER HAVING RADIALLY DISPOSED BLADES, SAID IMPELLER BLADES HAVING ENTRANCE ENDS AND DISCHARGE ENDS, A DIFFUSER COMPRISING A PLURALITY OF SPIRAL BLADES FORMING SPIRAL, OUTWARDLY FLARED DISCHARGE NOZZLES THEREBETWEEN, SAID DIFFUSER BLADES HAVING INNER ENTRANCE ENDS AND DISCHARGE OUTER ENDS, SAID DIFFUSER BLADES ENTRANCE ENDS BEING DISPOSED ADJACENT SAID IMPELLER BLADES DISCHARGE ENDS AND EACH HAVING A LAND EXTENDING A SUBSTANTIAL DISTANCE CIRCUMFERENTIALLY FROM ITS INNERMOST CUTOFF EDGE, SAID LANDS HAVING A FIXED RADIUS THROUGHOUT THEIR LENGTHS MEASURED FROM THE AXIS OF ROTATION OF SAID IMPELLER AND THE CIRCUMFERENTIAL LENGTH OF EACH OF SAID LANDS NOT EXCEEDING ONE HALF THE CIRCUMFERENTIAL DISTANCE BETWEEN THE CUTOFF EDGES OF SUCCESSIVE DIFFUSER BLADES, SAID HOUSING BEING INVOLUTE IN SHAPE AND HAVING AN ENTRANCE CHAMBER ADJACENT SAID IMPELLER 